• 한국소음진동공학회논문집
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• 제14권11호
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• pp.1115-1122
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• 2004

The paper discussed the effect of a tip mass on the stability of pipes on elastic foundations. Governing equations of motion are derived by extended Hamilton's principle, and the numerical scheme using finite element method is applied to obtain the discretized equations. With or without internal damping, the critical flow velocities of the pipes are investigated according to the variation of elastic foundation parameters and tip mass ratios. Also. the relationship between the eigenvalue branches and the corresponding flutter modes of the cantilevered pipes with a tip mass on the elastic foundations is fully investigated.

• 한국소음진동공학회논문집
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• 제12권1호
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• pp.57-64
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• 2002

Three kinds of viscoelastic damper model, which has a non-linear spring as an element is studied analytically and numerically The behavior of the damper model shows non-linear hysteresis curves which is qualitatively similar to those of real viscoelastic materials. The motion is governed by a non-linear constitutive equation and an additional equation of motion. Harmonic balance method is applied to get analytical solutions of the system. The frequency-response curves sallow that multiple solutions co-exist and that the jump phenomena can occur. In addition, it is shown that separate solution branch exists and that it can merge with the primary response curve. Saddle-node bifurcation sets explain the occurrences of such non-linear Phenomena.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.449-454
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• 2000

A three-parameter model of viscoelastic damper, which has a non-linear spring as an element is incorporated into an oscillator. The behavior of the damper model shows non-linear hysteresis curves which is qualitatively similar to those of real viscoelastic materials. The motion is governed by three-dimensional non-linear dynamical system of equations. The harmonic balance method is applied to get analytic solutions of the system. The frequency-response curves show that multiple solutions co-exist and that the jump phenomena can occur. In addition, it is shown that separate solution branch exists and that it can merge with the primary response curve. Saddle-node bifurcation sets explain the occurences of such non-linear phenomena. A direct time integration of the original equation of motion validifies the use of the harmonic balance method to this sort of problem.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.652-657
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• 2000

In this paper, Firstly, it is shown that the high vibration source of piping system is the pulsation transmission of pipe line element, such as, orifice plate, valves and the control valve is a broad band source and the branch wall and the cavity have vortex frequency. Secondly, in order to decrese the high vibration of piping system, some practical Friction damper with high damping have been developed and its effectiveness is investigated as installing it at piping system practically.

• 한국소음진동공학회논문집
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• 제13권12호
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• pp.956-964
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• 2003

The paper describes the relationship between the eigenvalue branches and the corresponding flutter modes of cantilevered pipes with a tip mass conveying fluid. Governing equations of motion are derived by extended Hamilton's principle, and the numerical scheme using finite element method is applied to obtain the discretized equations. The flutter configurations of the pipes at the critical flow velocities are drawn graphically at every twelfth period to define the order of quasi-mode of flutter configuration. The critical mass ratios, at which the transference of the eigenvalue branches related to flutter takes place. are definitely determined. Also, in the case of haying internal damping, the critical tip mass ratios, at which the consistency between eigenvalue braches and quasi-modes occurs. are thoroughly obtained.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.486-491
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• 2003

The paper presents the relationship between the eigenvalue branches and the corresponding flutter modes of cantilevered pipes conveying fluid. The pipes are located on elastic foundations which can be regarded as a soil model. In this paper, elastic foundations are assumed as linear distributed translational springs. Governing equations of motion are derived by extended Hamilton's principle, and the numerical scheme using finite element method is applied to obtain the discretized equations. The critical How velocity and stability maps of the pipe are investigated according to the variation of elastic foundation parameters, mass ratios of the pipe and internal damping Parameter. Also, the vibrational modes associated with flutter are shown.

• 한국컴퓨터정보학회논문지
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• 제4권4호
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• pp.34-39
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• 1999

본 논문에서는 이진 영상에서 경계에 발생하는 잡영을 효율적으로 제거하고 형상을 단순화시켜 윤곽선을 추출할 수 있는 방법을 제안하였다. 제안된 방법은 이진 영상에서 영역의 윤곽선을 구하는 기존의 $2{times}2$ 마스크 사용 방법을 일부 수정하여 한 픽셀 두께의 잡영을 효율적으로 제거할 수 있도록 하였다. 이를 위해 영역 경계의 잡영에서는 윤곽선 추적 경로가 중복되는 특성과 잡영의 끝점에서의 추적 특성을 분석하여 이용하였다. 또한 흰색 바탕을 윤곽선 추출에 활용함으로써 본래의 형상을 유지하며 효과적으로 단순화된 윤곽선 추출 결과를 얻을 수 있도록 하였다. 제안된 방법은 다양한 실험을 통해 그 효용성을 확인하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.665-669
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• 2003

The paper deals with the relationship between the eigenvalue branches and the corresponding flutter modes of cantilevered pipes with a tip mass conveying fluid. Governing equations of motion are derived by extended Hamilton's principle, and the numerical scheme using finite element method is applied to obtain the discretized equations. The order of branches and unstable modes associated with flutter are defined in the stability maps of mass ratios of the pipe and the critical flow velocity. As a result, the relationship between the flutter related to the eigenvalue branches and the flutter modes are investigated thoroughly.

• 한국조사연구학회:학술대회논문집
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• 한국조사연구학회 2001년도 춘계학술논문발표대회 발표논문집
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• pp.95-108
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• 2001

본 연구는 주유소와 가전제품취급점이 직영점과 대리점의 양대 유통체제를 가지고 있다는 사실에 착안하여 갈등발생요인과 갈등과의 관계, 갈등이 경영성과에 미치는 영향을 파악하므로써 유통환경내에서 중점적으로 관리되어야 할 갈등원인을 규명하고 이에 따른 갈등이 경영성과에 미치는 영향을 파악해 보고자 하였다. 본 연구의 분석결과를 요약해 보면, 첫째, 주유소와 가전제품취급점이 갖고 있는 갈등원인 중 힘의 불균형, 본사의 역할불이행, 가맹점의 역할불이행, 지각의 차이, 의사소통의 장애는 갈등과 정의 관계를 가지나 역할명확성은 갈등과 부의 관계를 가지는 것으로 나타났으며 이러한 결과는 본사의 일방적 힘의 행사정도가 강할수록, 본사와 가맹점이 서로의 역할을 수행하는 정도가 떨어질수록, 가맹점 취급의 공정성이나 가맹점 지원이 부족할수록, 가맹점 요청에 대한 반응이 부적절하거나 정보의 전달정도가 떨어질수록 갈등이 더 많이 발생한다는 것을 의미한다고 할 수 있겠다. 또한 갈등에 가장 큰 영향을 미치는 갈등원인은 의사소통의 장애로 나타났으며 마지막으로 본 연구의 유통관리적 의미와 시사점에 대하여도 기술하였다.

• 한국정보전자통신기술학회논문지
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• 제13권2호
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• pp.113-122
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• 2020

Noise affects the accuracy of three-dimensional shape recovery. Its occurrence is unpredictable and depends on several mechanical, environmental, and other factors. When two-dimensional image sequences are obtained for shape from focus (SFF), mechanical vibration occurs in the translational stage, causing an error in the three-dimensional shape recovery. To address this issue, mechanical vibration is modeled using Newton's second law and the principle of the rack and pinion gear. Then, an optimal sampling step size considering the mechanical vibration is suggested through theoretical demonstration. Experiments conducted with real objects verify the effectiveness of the proposed sampling step size. In this paper, in a realistic environment with noise, the potential of obtaining more accurate three-dimensional reconstruction results of the objects is explored by acquiring the optimal sampling step size, which improves the sampling step size relative to those reported in a previous study performed under similar conditions.